Outline
         Introduction to                 p What is a network?
           Networking                    p Need of a...
Local Area Network (LAN)                      Wide Area Networks (WAN)
pA  single collection of machines &           p Con...
A Simple Peer-to-Peer Network              Peer to Peer Advantages
                                           p Easy to in...
Server Based Disadvantages                    Specialized Servers
 p Server failure results in unusable           p Indivi...
Advantages of Bus Topology                 Disadvantages of Bus Topology
p Works    well for small networks         p Mana...
Ring Topology                             Ring Topology
pA  ring topology is a network in the
  shape of a ring or circle,...
Mesh Topology                                       LAN implementation
    p   Every device interconnected                ...
Token Ring   FDDI/CDDI
             p   FDDI – Fibre Distributed Data Interface
                 n   Is a fibre optic base...
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Introduction to Networking

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Introduction to Networking

  1. 1. Outline Introduction to p What is a network? Networking p Need of a network p LAN & WAN DCS201- Computer Science p Networking Terminology n Client/Server relationship n Peer-to-peer networks By: p Network Topologies Dilum Bandara n Bus , Star, Ring, Mesh What is a network? Need of a network p Whenmore than one computer is p Resource sharing connected it forms a Network n Achieved by sharing devices such as Printers, scanners, centralised file storage p Data sharing n Exchange information n Route data from user to user n Use E-mail to communicate A Simple Network Early Networks p Early networks were custom built p Connecting few computers & having 1 or 2 peripherals p Early Ethernet n 30 users n total span of 600 feet 1
  2. 2. Local Area Network (LAN) Wide Area Networks (WAN) pA single collection of machines & p Connects two or more separate peripherals locations which are miles of distance p Around 100 computers apart p Distance spanned less than 1000 feet p Down the road or across the world p Basic building block for larger n E.g: Microsoft, Federal Express, DHL networks p Areconnected using Fiber or n Called the Internetwork Microwave links p Use cables like UTP Cat5 & Coaxial Client/Server relationship Client Server Networks 1. Client requests shared resources p Server controlled communication 2. Server responds & shares resources p Centralised CPU power & storage 1 capacity p Examples for servers: 2 n Windows NT/Windows 2000/2003 n Novell Network Types Peer to Peer p Peer to Peer p No centralized control n Client/Server role interchanges p Act as both client & server n Windows 2000/XP p User controls access to machine n Windows for Workgroups p Disordered management p Security concerns p Adding machines slows network down 2
  3. 3. A Simple Peer-to-Peer Network Peer to Peer Advantages p Easy to install & configure p Users control individual shared resources p Lower setup & operations cost p No need of a network administrator p Best for 10-20 users Peer to Peer Disadvantages Server Based Networks p Security for only a single resource at p Server is the key a time n Controls the communication p Users may need to know many p Centralized control of resources passwords p Better & reliable resources p Individual machine backups n Faster processors p Speed decreases while sharing n More memory p No central location/access of data n Extra peripherals Server Network Server Based Advantages p Centralized management of n Security n User accounts n Access p Simplify network administration p Powerful, efficient access to resources p Single password for each user p Best for n High level of use n Large number of users n Large networks 3
  4. 4. Server Based Disadvantages Specialized Servers p Server failure results in unusable p Individual services supplied network n Web Servers p Server failure results in loss of n Communication Servers Mail Servers resources p p Messaging servers p Expert staff to manage increases n File & Print Servers cost n Application Servers p Dedicated hardware increases cost n Domain Controllers/Directory Servers p Dedicated software increases cost n Fax Servers Network Topologies Network Topologies A topology is a way of “laying out the p Bus network” p Star p Physical topologies describe how the cables are run in the network p Ring p Mesh p Logical topologies describe how the data or network messages travel p Hybrid Bus Topology Bus Topology pA bus topology is a network configured so that nodes are connected to a segment of cable in the logical shape of a line, with a terminator at each end p Uses coaxial cables with BNC connectors 4
  5. 5. Advantages of Bus Topology Disadvantages of Bus Topology p Works well for small networks p Management costs often too high p Inexpensive to implement on a small p Difficult to isolate a malfunctioning scale node or cable segment & associated p Requires less cable connectors p Easy to add another workstation p Possiblefor defective node to take down the entire network p Subject to congestion from network traffic Star Topology Star Topology p The star topology is a network configured with a central hub & individual cable segments connected to the hub, like the shape of a star p A hub is a central device used in the star topology that joins single cable segments or individual LANs into one Hub network p Normally uses UTP Cat5 Advantages of Star Topology Disadvantages of Star Topology p Easier to manage than a bus p Susceptible to a single point of p Easier to locate node & cable failure problems p Requires more network cable at the p Easier to expand than a bus or ring, start than a bus especially for enterprise networking p Well suited for expansion into high- speed networking p More equipment options 5
  6. 6. Ring Topology Ring Topology pA ring topology is a network in the shape of a ring or circle, with nodes connected around the ring p Normally use coaxial cables & BNC connectors Ring p Also used in fiber networks Advantages of Ring Topology Disadvantages of Ring Topology p Easier to manage than a bus p Requires more network cable & p Easier to locate node & cable equipment at the start than a bus problems compared to Bus p Not as many equipment options as p Good over long distances for a bus p Handles high-volume traffic well p Not as widely used as the bus p Very reliable topology Hybrid (Bus-Star) Mesh Topology Hub Hub 6
  7. 7. Mesh Topology LAN implementation p Every device interconnected p Three technologies n Ethernet – IEEE802.3 p Most expensive n Token Ring – IEEE802.5 p Best in fault tolerant n FDDI/CDDI n Cable fault tolerant n Device fault tolerant p The Internet uses Mesh Topology Ethernet Ethernet p Is a LAN specification developed by Xerox, Intel & Digital p Based on the CSMA -C D n Carrier Sense Multiple Access – Collision Detection p Ethernet & IEEE802.3 are very similar protocols p Uses the bus topology p Runs at speeds of 10/100/1000 Mbps CSMA-CD Token Ring/IEEE 802.5 p Is a Token passing LAN technology that makes use of the ring topology p Runs at 4/16Mbps 7
  8. 8. Token Ring FDDI/CDDI p FDDI – Fibre Distributed Data Interface n Is a fibre optic based protocol that uses the ring topology n Runs at 100Mbps p CDDI – Copper Distributed Data Interface n Is a copper based protocol that uses the ring topology n Runs at 100Mbps p Both of these standards use dual ring architecture for high speed & reliability FDDI/CDDI Summary p What is a network? p Need for a network p LAN & WAN p Networking Terminology n Client/Server relationship n Peer-to-peer p Network Topologies n Bus , Star, Ring, Mesh 8

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